Automatic balance-beam hinged shutter gate



Jan. 8, 1957 A. FORTES 2,776,541

AUTOMATIC BALANCE-BEAM HINGED SHUTTER GATE Filed Feb. 24, 1953 INVENTOR//VGELO 'YFUA7ZIS) ATTORNEYS Patented Jan. 55, F957 AUTOMATICBALANCE-BEAM HINGED SHUTTER GATE Angelo Fortes, Estoril, PortugalApplication February 24, 1953, Serial No. 333,510

1 Claim. (Cl. 61-25) The invention relates to an improvement inautomatic balance-beam hinged shutter gates of the type in which one endof a balance-beam is connected to a counterweight and the other isconnected to the upper or free end of a hinged shutter gate which issubjected to the force of the water to be controlled in regulating thelevel of a pool for example.

The known gates of this type operate well under good conditions, but ithas been found that they cease to operate correctly when the tail watersback up against the downstream face of the gate and exert a pressurewhich decreases the forces acting on the gate in a direction to open itin relation to the counterweight. When, for example, the gate is placedon the bed of a river with the pivotal axis near the river bed and therelationship between the counterweight and the other parts is adjustedto maintain a certain level on the upstream side of the gate, a heavyflow in the river results in the opening of the gate to such an extentthat the downstream level rises until the tail waters exert ahydrostatic pressure which upsets the equilibrium of the system. Thecounterweight, which has been adjusted to balance only the pressure onthe upstream side of the gate, then becomes preponderant and closes thegate whereas it is desirable to maintain it open so long as the floodconditions continue.

There are balance-beam type hinged shutter gates operating on theprinciple of water chambers with adjustable flow, which have the objectof more or less reducing the above mentioned disadvantage. In thesegates, the counterweights are displaced inside wells fed by a weir fromthe upstream side, and comprising an adjustable outlet in the form of atube opening out on the downstream side. The top of the weir is adjustedto the mark of the level which it is intended to maintain on theupstream side or a slightly lower mark. If the level on the upstreamside tends to exceed the said level, a certain flow will pass over theweir. With the outlet tube producing a considerable loss of head thelevel rises in the wells and, lightening the counterweight through theArchimedean pressure, assists the gate to lower itself. It will be seenthat, in this system, the outlet tubes can become obstructed and causethe opening of the gate at the wrong time and, further there is thedisadvantage of the complicated installation comprising the weir andvarious tubes.

The present invention has for its objects to provide an improvedarrangement for controlling automatic balancebeam type hinged shuttergates intended to regulate a pool level on the upstream side andsubjected to the pressure of the tail waters, by means of which thedisadvantages of the foregoing arrangement and the difiiculties ofcarrying the same into effect are obviated. The arrangement according tothe invention permits the regulation of the level where there are slightflows, as in the case of conventional hinged shutter gates, and rendersit possible to obtain complete opening for large flows, whatever may bethe level of the water on the gate. Thus according to the inventionmeans operatively connected to the counterweight side of thebalance-beam, which may be the counterweight or counterweights, or otherfioatable means alone or in combination with the counterweight(s), isarranged to be subjected, when the level of the tail waters exceeds agiven level, to the hydrostatic action of a body of liquid the level ofwhich varies in accordance with that of the tail waters. Thiscontrolling action is designed to neutralize the effect of the pressureof the downstream waters on the shutter.

Other objects and features of the invention will appear from thefollowing description of when considered in connection with the attacheddrawing in which Fig. 1 is a side elevation of one embodiment of thepresent invention and Fig. 2 is a plan view thereof. A indicates the bedof the channel confining the headwaters to be controlled, B indicatesthe headwaters, C indicates the masonry at one side of the channel and Dindicates the tail waters. It is conventional to provide balance beamand counterweight control apparatus at each side of the channel but inthe following description reference will be made to the parts andconnections of the control apparatus at one side only.

The conventional shutter gate 1 is pivoted at its lower side to providea hinged mounting 2 carried by the bed A of the channel. A balance-beam3 is pivoted at 4 on the masonry C and one side of the beam 3 isconnected to the upper or free end of the gate 1 by means of a stay 5which is preferably adjustable in length and is pivotally connected at 6to the gate 1 and at 7 to the beam 3. A counterweight or a plurality ofcounter weights (herein referred to for convenience as a counterweight)8 is suspended from the other side of the balancebeam 3 by means of astay 9 connected to the beam 3 at 10. The stay 9 is longitudinallyadjustable and it is adapted to transmit to the beam upwardly directedforces exerted on the counterweight 8 by the hydrostatic action of thetail waters B when the tail waters rise above a predetermined level.

The operation is as follows:

When the fiow required in order to maintain the pool level on theupstream side is small and does not cause the water level on thedownstream side to rise above a' given level, e. g. the level of thepivots, the gate operates exactly like conventional automaticbalance-beam type hinged shutter gates, that is to say, the pressurewhich the waters on the upstream side exerts on the gate causes a momenttending to make the gate open, which is counterbalanced, together withthe moment of the movable parts, by the moment produced by the action ofthe counterweight, which is completely above the tail water; the gate istherefore balanced and maintains its position.

In the event of the fiow increasing slightly, the level of the pooltends to rise, thus causing a greater pressure on the gate; the momentof this pressure consequently becomes greater than the moment of thecounterweight and the gate commences to open, partially opposing therise in the pool level; the pressure or thrust moments on the upstreamside and of the counterweight vary simultaneously according to theopening of the gate and, finally, the gate is stabilized in a newposition (lower than the initial position) in which the moment of thecounterweight balances the moment of the pressure. A pool level veryslightly higher than the initial level will correspond to the newposition of the gate. On the as sumption that small flows are involved,to which correspond downstream levels lower than the level of thepivots, the counterweight remains above the downstream water level andthe gate continues to operate exactly like conventional balance-beamtype hinged leaf gates.

if, on the contrary, the flow to be carried off should decrease insteadof increasing, the same action takes place, but in the reverse sense.

Let us now consider the case in which a greater flow is to he carriedoff and the tail water is established at a level a little hi her thanthe level of the pivots. The gate is in a more open position than thatin the case of the above-mentioned flows. According to the invention thestay 9 is adjusted so that the bottom of the counterweight 8 is in theimmediate vicinity of the downstream water level. If this were not so,the moment due to the pressure of the downstream waters, which increaseswith the flow to be carried off and with the opening of the gate, wouldhinder the opening of the latter. According to the invention, when thegate. opens, the counterweight rises as in any balance-beam type hingedshutter gate, but, in the case of the flow under consideration, thecounterweight is at the mark of the downstream water level, as hasalready been mentioned, and its vertical course is calculated so thatthe rise of the counterweight as a function of the opening of the gateis less than the corresponding rise of the downstream level. Thus, whenthe flow to be carried off increases, the said counterweight issubjected by the tail waters, to a hydrostatic pressure which is all thegreater the higher the. level of the tail water, and which, bylightening the counterweight, compensates the unfavourable effect of thepressure exerted by the said waters on the downstream side of the gate.

Thus, when the flow increases beyond the normal flow, the level of thepool tends to rise which increase the pressure on the upstream face ofthe gate, in consequence of which the gate commences to open. When thegate opens, the downstream level rises. In the conventional hingedshutter gate system, the rise in the downstream level will cause anincrease in the pressure on the downstream face of the gate which willlimit the opening of the gate or act so as to cause the gate to closeaccording to whether the reaction of the downstream water level is moreor less rapid. According to the invention, the rise in the downstreamlevel increasing the hydrostatic pressure on the counterweight 8lightens it, thus compensating the effect of the pressure of the tailwaters on the gate so that it will open normally.

The hinged shutter gate according to the invention wil continue to open,in proportion to the increase in the flow, the action of the downstreamlevel on the counterweight becoming greater, until, for the maximumflow, with the counterweight floating completely in the tail water, thegate is completely open, even if there is no appreciable diiterence inlevel between upstream and downstream, whereas a conventional hingedshutter gate would cause, for the same flow, a considerable differencein level, since, in order to balance the action of the counterweight, itrequires a snfiicient ditference in pressure between its upstream anddownstream faces.

In the hinged shutter gate shown diagrammatically in the accompanyingdrawing, the counterweight 8 is located on the downstream side of thegate (an arrangement which distinguishes the balance-beam type hingedshutter gates which are the object of the invention even more clearlyfrom the conventional balance-beam type hinged shutter gates), whichenables them to be protected from the current which passes over the gateby means of simple guide walls which undergo practically no unbalancedwater pressure. Other embodiments are however within the contemplationof the invention. Thus the counterweights or separate fioatable meansmay be located on the upstream side of the gate provided that they arearranged to be subjected to the hydrostatic action of a body of. liquidof the same level as the tailwater. Thu the counterweights may bearranged for immersion in a pool on the upstream side of the gate butconnected to the tailwaters by a suitable channel.

it is also within the contemplation of the invention to arrange for theimmersion of the connterweights in wells capable of being isolated bothfrom the head-water and the tail water so that the gate may be loweredat will by filling the wells with water.

Furthermore, one or more independent floats may be associated with oneor more co-unterweights and the gate may be controlled from one sideonly in. which case it is necessary to provide a gate which is resistantto torsion.

What I claim as my invention is:

An automatic balance beam shutter gate for regulating the level ofheadwaters independently of the level of tailwaters comprising, ashutter gate hingedly mounted at the lower edge thereof for pivotalmovement in a vertical plane, said shutter gate being adapted to open inresponse to pressure of headwaters, a balance beam, means connecting oneend of said balance beam with the upper edge of said shutter gate, acounterweight, a rigid stay connecting the counterweight with the otherend of the balance beam, said counterweight retaining said shuttel-gateclosed when the headwaters elevation is below a predetermined level,said counterweight being suspended above a body of liquid the level ofwhich varies as the level of the tailwaters whereby as the tailwatersrise and increase the pressure on the downstream side of the shuttergate the counterweight becomes at least partially immersed thuscompensating for the increase in tailwater pressure and offers lessresistance to the opening of the shutter gate.

References Cited in the file of this patent UNITED STATES PATENTS367,038 Harding July 26, 1887 970,308 Collar Sept. 13, 1910 973,172Collar -a Oct. 18, 1910 2,168,117 Danel Aug. 1, 1939 2,645,089 Ponsar a-July 14, 1953

